Various raw materials including crude oil are a mixture of various materials, for example, various compounds. These raw materials can be generally divided into the respective compounds and then used. A representative process of separating the mixture is a distillation process.
For example, the mixture may be distilled by passing through one or more distillation columns. In the distillation process, a part of a flow or the entire flow may be fed back to the distillation columns after passing through a condenser or a reboiler. Through this process, high-purity compounds can be obtained. In general, a raw material including a material having three or more components can be divided into each component by passing through two or more distillation columns. For example, a low boiling point component can be primarily separated from the raw material at an upper part of a first distillation column, and an intermediate boiling point component and a high boiling point component can be separated from the raw material at upper and lower parts of a second distillation column connected to the first distillation column. In this case, remixing of intermediate boiling point components may occur in a lower area of the first distillation column. Thus, additional energy consumption may occur.